Audio reproduction has become increasingly complex and varied in recent decades. Traditionally audio was reproduced as a single mono signal or possibly as a spatial two channel (stereo) signal. Furthermore, modification and adaptation of audio was typically limited to level adjustments or equalization. However, nowadays many different and complex audio systems are widely used including spatial audio systems, such as e.g. surround sound home cinema systems. Furthermore, signal processing and adaptation has become increasingly complex and advanced signal processing has been used to adjust various parameters of the rendered sound including for example relative delay differences between channels, emphasis of speech etc.
However, there is still a desire to further develop, enhance and improve audio rendering and reproduction. Indeed, there is still a drive to develop further approaches for allowing improved, or more varied audio signals to be provided to a user. In particular, sound rendering proving an improved spatial user experience is highly desirable.
Indeed, it has recently been proposed to enhance conventional two-dimensional spatial audio systems (such as 5.1 surround sound systems) with additional loudspeakers that are out of the horizontal two dimensional plane. Specifically, it has been proposed to add elevated front speakers that are positioned higher than the traditional front (or center) speakers. However, as audio content is typically only available in traditional two-dimensional surround sound formats, it is necessary to generate these elevated sound channels from the existing two-dimensional channels. It has been proposed to generate such elevated sound channels based on the correlation between signal components in different channels. However, the current approaches tend not to provide optimal performance, and in many cases result in a spatial experience which is not as convincing as would be desired. Indeed, typically the spatial effect of the elevated speakers is considered not to be significant enough.
Essentially the same restrictions typically also apply to loudspeakers placed at extreme sides of the listening area and virtual surround loudspeakers that can be created by directional sound reproduction methods (e.g., directional reproduction using walls and other surfaces of the room as sound reflectors), and by elimination of the sound in a desired direction (e.g., using an acoustic dipole source).
Hence, an improved audio system would be advantageous and in particular a system allowing increased flexibility, new or improved audio effects, improved adaptation and/or modifications of the rendered audio, an improved spatial experience, improved generation of additional spatial channels (and in particular elevated channels) and/or improved performance would be advantageous.